An internal combustion engine generally combusts a fuel to produce mechanical power. Introduction of the fuel into a cylinder of the internal combustion engine is most commonly achieved using a fuel injector. A commonly used injector is a closed-nozzle injector which includes a nozzle assembly having a spring-biased needle valve element positioned adjacent an injector nozzle for allowing the fuel to be injected into the cylinder of the internal combustion engine. The needle valve element moves to allow the fuel to pass through the injector nozzle and out of injector orifices or spray holes, thus marking the beginning of a fuel injection event.
Dual fuel engines typically may have an injector with two nozzles placed adjacent to each other where a pilot injection of a diesel fuel and injection of a gaseous or liquid fuel may occur through the separate nozzles. The diesel fuel is primarily responsible for starting the ignition. However, when the two nozzles are adjacent to each other, it may be possible that some amount of the gaseous fuel may not come in contact with the diesel fuel, and subsequently leads to poor combustion characteristics which, in turn, may lead to higher emission levels.
German Patent Application Number DE 10200/4021538 describes a fluid flow control valve. The fluid flow control valve includes two coaxial valve needles. An inner needle is completely enclosed, inside an outer needle. Flow of fuel to jets in the outer needle is blocked by the inner needle. Large diameter jets in the hollow conical nozzle body are provided in line with the jets in the outer needle. The outer needle blocks additional flow to jets in a conical nozzle. The inner and the outer needles together provide a set of injection openings to inject fuel into the combustion chamber.